--isvoid

Class A{
   r:Undef;
   s:D;
   a():Int{
	{
	isvoid new Undef;  -- undefined type
	let a:Undef <- isvoid r in
	    a<- isvoid (new Undef);
	r <- isvoid (new Undef);
	isvoid (undef);
	isvoid(new D);
	isvoid(new Undef);
        while isvoid(1) loop isvoid(r) pool;
	if isvoid(r) then isvoid(s) else isvoid(q) fi;
	case isvoid(s) of
		q:Int => isvoid(q);
		y:Undef => isvoid(y);
	esac;
	s.f(isvoid(true));
	s.c(isvoid(1));
	s.d(isvoid(1));
	s.c(isvoid(s.f(true)));
	s.d(isvoid(s.f(true)));
	s.c(isvoid(s.g(true)));
	s.d(isvoid(s.g(true)));
	}
	};
};

Class D inherits C{
   c(i:Int):Bool {
	true
	};
   d(i:Bool):Bool {
	true
	};
};

Class C{
   f(k:Bool):Bool {
	true
	};
   g(k:Bool):Int {
	1
	};
};

Class Main{
   main():Object{
	1
	};
};